No warning was issued by PNG authorities to the public that armed US security contractors would be engaged in policing until the photos emerged on social media over the weekend.

“We invited them into PNG in early February this year, they did a presentation, which included other government departments, and they displayed to us the capabilities that they would be able to provide to PNG,” Commissioner Baki said.

“What they’re doing is observation and training assistance here, in (Port Moresby). We haven't sent them out to other parts of the country.”

The five members of little-known US contractor Laurence Aviation and Security Group (LASG) have been stood down but remain in Port Moresby.

Dr John Coyne, from the Australian Strategic Policy Institute (ASPI), is a former senior AFP officer who has served in PNG.

“It's strange and there wouldn’t seem to be any legal basis for these private military contractors to carry with them firearms nor to undertake raids,” he said.

"There's been no announcement of legislative changes and we saw this the last time the AFP operations were suspended in PNG, the issue was about carrying firearms on patrols.

“We should be concerned and people are asking the question: are these guys special forces in support of APEC (due in Moresby next year)? Are they Australian? Where are they from? And what are they doing?”